Most researches associated with cell death have been concentrated on apoptosis of cells, also known as programmed cell death (PCD). With the discovery of the enzyme caspase, a number of pharmaceutical companies have promoted the development of drugs utilizing caspase inhibitors during the past 10 years. However, the current status is that there have hardly been any of these drugs approved by FDA. This is because the apoptosis of cells is a cell death which occurs under physiological circumstances and such a cell death may be probably due to the defense mechanism for maintaining homeostasis in the body. In contrast, necrosis is a cell death which mainly occurs under morbid circumstances, and in most cases it is characterized by accompanying the inflammatory response. Necrosis has been known as an uncontrolled cell death for a long time, but a recent research (Proskurykakov S Y et al. 2002, Biochemistry) reported the necrosis as an active/controlled cell death. Typical diseases caused by necrosis include ischemic (e.g. myocardial infarction, stroke, renal infarction), neurodegenerative, and inflammatory diseases. Since it is believed that necrosis is an uncontrolled, accidental cell death under morbid circumstances, researches on the functional mechanism, molecular targets, signal transduction systems, etc. thereof have rarely been conducted. Thus, there arises a compelling need to discover and develop the necrosis-inhibiting substances for the treatment of ischemic, neurodegenerative, and inflammatory diseases which are caused by necrosis, and to elucidate the biological, pathological causes of necrosis.
The indole derivatives according to the present invention have very useful structures from a medical viewpoint and many publications have reported the research results with reference to these structures. Among the research results, the following are the most representative of all: the patent WO2006/112549 reported some indole derivatives having the activity for the glucokinase, the patent WO95/07276 reported those useful as anti-tumor agents and as inhibitors against the production of cardiovascular system, and the patent WO2004/018428 reported those useful as antibiotics.